| Partâ… :Recombinant Human Keratinocyte growth factor-2 protects ventilator-induced lung injury in ratsObjective To build the model of ventilator induced lung injury (VILI) in rats in vivo and to investigate the effects of Recombinant human Keratinocyte growth factor-2 against VILI. Methods 40 specified-pathogens free male Sprague-Dawley rats were randomized into four groups:Group Control:with non-ventilation; Group LV: with low Vt ventilation(VT=6ml/kg,70 breathes/min,PEEP=3 cmH20 and FiO2=21%);Group VILI, an injurious strategy, using a high VT and no PEEP(20ml/kg,70 breathes/min, PEEP=0 and Fi02=21%);Group rhKGF-2+VILI:rhKGF-2 pretreatment group, rats were pretreated with rhKGF-2 5mg/kg intratracheally 72h before high tidal volume ventilation. After 4h of ventilation, all rats were killed by exanguination and the samples were obtained.Arterial blood gas analysis,the wet/dry weight ratio of lung(W/D),the levels of total proteins, the total cell count and the neutrophil count in bronchoalveolar lavage fluid(BALF)were examined.Furthermore, the pathological change of lung was observed under light microscope and electron microscope, and the lung injury score was also evaluated. Results After 4h mechanical ventilation, PaO2 of the VILI group was significantly lower than those of the control group and the low tidal volume group (p<0.05). Compared with VILI group, PaO2 of the rhKGF-2+VILI group was significantly increased (p<0.05); The W/D ratio of lung, lung injury score, the levels of total proteins,the numbers of total cells and neutrophils in the BALF of VILI group were significantly higher than those of the control group and the low tidal volume group (p<0.05). Compared with VILI group, those of the rhKGF-2+VILI group were significantly decreased (p<0.05). However, no statistical difference could be found between the low tidal volume group and the control group (p>0.05).There were widespread alveolar walls thickening, massive neutrophils infiltration, hemorrhage and hyaline member forming under light microscope in the VILI group. Under electron microscope,the alveolar epithelial cells and the alveolar-capillary barrier were severe injuried in the VILI group. But in the rhKGF-2+VILI group, the lung injury was mild as compared with the VILI group under light microscope and electron microscope. There were no obvious pathologic differences between the low tidal volume group and the control group.Conclusions Rats showed obvious lung injury after mechanical ventilation for 4h with 20ml/kg tidal volume. Pretreatment with 5mg/kg rhKGF-2 intratracheally 72h before mechanical ventilation would attenuate VILI induced by high tidal volume ventilation.Part II:The mechanism of profective effect of rhKGF-2 on ventilator-induced lung injury in ratsObjective In this study, we explored the possible mechanism of the profective effect of rhKGF-2 on ventilator-induced lung injury in rats. Methods 40 specified-pathogens free male Sprague-Dawley rats were randomized into four groups:Group Control:with non-ventilation; Group rhKGF-2:with non-ventilation but pretreatment with rhKGF-2 5mg/kg intratracheally 72h before modeling;Group VILI, an injurious strategy, using a high Vt and no PEEP(20ml/kg, 70 breathes/min, PEEP=0 and Fi02=21%);Group rhKGF-2+VILI:rhKGF-2 pretreatment group, rats were pretreated with rhKGF-2 5mg/kg intratracheally 72h before high tidal volume ventilation. After 4h of ventilation, all rats were killed by exanguination and the samples were obtained. The myeloperoxidase (MPO) activity in the lung tissue, the levels of TNF-a and MIP-2 in the BALF were measured respectively. SP-A, SP-B and SP-C mRNA were determined by RT-PCR, SP-C protein were measured by western blot. To examine the role of rhKGF-2 in the proliferation of alveolar typeâ…¡cells (ATâ…¡),immunohistochemical staining for SP-C was performed. Results The MPO activity of lung, the levels of TNF-a and MIP-2 in the BALF of VILI group were significantly higher than those of the control group (p <0.05).Compared with VILI group, those of the rhKGF-2+VILI group were significantly decreased (p<0.05). No statistical difference could be found between the rhKGF-2 group and the control group (p>0.05).However, the level of SP-A, SP-B, SP-C mRNA, SP-C protein and the numbers of ATâ…¡of the VILI group were significantly lower than those of the control group (p<0.05).Compared with VILI group, those of the rhKGF-2+VILI group were significantly increased (p<0.05).And in the rhKGF-2 group, the level of SP-A, SP-B, SP-C mRNA, SP-C protein and the numbers of ATâ…¡were significantly higher than those of the control group (p <0.05).Conclusions This study demonstrated that rhKGF-2 contributed to the alveolar typeâ…¡cells metaplasia, and has potential therapeutic role in VILI by inhibiting inflammatory cytokine expression, attenuating neutrophil infiltration and activation and promoting alveolar typeâ…¡cells metaplasia and surfactant protein production. |
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